Move base/prefs to components/prefs

base/prefs/pref_member.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-//
-// A helper class that stays in sync with a preference (bool, int, real,
-// string or filepath).  For example:
-//
-// class MyClass {
-//  public:
-//   MyClass(PrefService* prefs) {
-//     my_string_.Init(prefs::kHomePage, prefs);
-//   }
-//  private:
-//   StringPrefMember my_string_;
-// };
-//
-// my_string_ should stay in sync with the prefs::kHomePage pref and will
-// update if either the pref changes or if my_string_.SetValue is called.
-//
-// An optional observer can be passed into the Init method which can be used to
-// notify MyClass of changes. Note that if you use SetValue(), the observer
-// will not be notified.
 
-#ifndef BASE_PREFS_PREF_MEMBER_H_
-#define BASE_PREFS_PREF_MEMBER_H_
-
-#include <string>
-#include <vector>
-
-#include "base/bind.h"
-#include "base/callback_forward.h"
-#include "base/files/file_path.h"
-#include "base/logging.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/prefs/base_prefs_export.h"
-#include "base/prefs/pref_observer.h"
-#include "base/single_thread_task_runner.h"
-#include "base/values.h"
-
-class PrefService;
-
-namespace subtle {
-
-class BASE_PREFS_EXPORT PrefMemberBase : public PrefObserver {
- public:
-  // Type of callback you can register if you need to know the name of
-  // the pref that is changing.
-  typedef base::Callback<void(const std::string&)> NamedChangeCallback;
-
-  PrefService* prefs() { return prefs_; }
-  const PrefService* prefs() const { return prefs_; }
-
- protected:
-  class BASE_PREFS_EXPORT Internal
-      : public base::RefCountedThreadSafe<Internal> {
-   public:
-    Internal();
-
-    // Update the value, either by calling |UpdateValueInternal| directly
-    // or by dispatching to the right thread.
-    // Takes ownership of |value|.
-    void UpdateValue(base::Value* value,
-                     bool is_managed,
-                     bool is_user_modifiable,
-                     const base::Closure& callback) const;
-
-    void MoveToThread(scoped_refptr<base::SingleThreadTaskRunner> task_runner);
-
-    // See PrefMember<> for description.
-    bool IsManaged() const {
-      return is_managed_;
-    }
-
-    bool IsUserModifiable() const {
-      return is_user_modifiable_;
-    }
-
-   protected:
-    friend class base::RefCountedThreadSafe<Internal>;
-    virtual ~Internal();
-
-    void CheckOnCorrectThread() const {
-      DCHECK(IsOnCorrectThread());
-    }
-
-   private:
-    // This method actually updates the value. It should only be called from
-    // the thread the PrefMember is on.
-    virtual bool UpdateValueInternal(const base::Value& value) const = 0;
-
-    bool IsOnCorrectThread() const;
-
-    scoped_refptr<base::SingleThreadTaskRunner> thread_task_runner_;
-    mutable bool is_managed_;
-    mutable bool is_user_modifiable_;
-
-    DISALLOW_COPY_AND_ASSIGN(Internal);
-  };
-
-  PrefMemberBase();
-  virtual ~PrefMemberBase();
-
-  // See PrefMember<> for description.
-  void Init(const std::string& pref_name,
-            PrefService* prefs,
-            const NamedChangeCallback& observer);
-  void Init(const std::string& pref_name, PrefService* prefs);
-
-  virtual void CreateInternal() const = 0;
-
-  // See PrefMember<> for description.
-  void Destroy();
-
-  void MoveToThread(scoped_refptr<base::SingleThreadTaskRunner> task_runner);
-
-  // PrefObserver
-  void OnPreferenceChanged(PrefService* service,
-                           const std::string& pref_name) override;
-
-  void VerifyValuePrefName() const {
-    DCHECK(!pref_name_.empty());
-  }
-
-  // This method is used to do the actual sync with the preference.
-  // Note: it is logically const, because it doesn't modify the state
-  // seen by the outside world. It is just doing a lazy load behind the scenes.
-  void UpdateValueFromPref(const base::Closure& callback) const;
-
-  // Verifies the preference name, and lazily loads the preference value if
-  // it hasn't been loaded yet.
-  void VerifyPref() const;
-
-  const std::string& pref_name() const { return pref_name_; }
-
-  virtual Internal* internal() const = 0;
-
-  // Used to allow registering plain base::Closure callbacks.
-  static void InvokeUnnamedCallback(const base::Closure& callback,
-                                    const std::string& pref_name);
-
- private:
-  // Ordered the members to compact the class instance.
-  std::string pref_name_;
-  NamedChangeCallback observer_;
-  PrefService* prefs_;
-
- protected:
-  bool setting_value_;
-};
-
-// This function implements StringListPrefMember::UpdateValue().
-// It is exposed here for testing purposes.
-bool BASE_PREFS_EXPORT PrefMemberVectorStringUpdate(
-    const base::Value& value,
-    std::vector<std::string>* string_vector);
-
-}  // namespace subtle
-
-template <typename ValueType>
-class PrefMember : public subtle::PrefMemberBase {
- public:
-  // Defer initialization to an Init method so it's easy to make this class be
-  // a member variable.
-  PrefMember() {}
-  virtual ~PrefMember() {}
-
-  // Do the actual initialization of the class.  Use the two-parameter
-  // version if you don't want any notifications of changes.  This
-  // method should only be called on the UI thread.
-  void Init(const std::string& pref_name,
-            PrefService* prefs,
-            const NamedChangeCallback& observer) {
-    subtle::PrefMemberBase::Init(pref_name, prefs, observer);
-  }
-  void Init(const std::string& pref_name,
-            PrefService* prefs,
-            const base::Closure& observer) {
-    subtle::PrefMemberBase::Init(
-        pref_name, prefs,
-        base::Bind(&PrefMemberBase::InvokeUnnamedCallback, observer));
-  }
-  void Init(const std::string& pref_name, PrefService* prefs) {
-    subtle::PrefMemberBase::Init(pref_name, prefs);
-  }
-
-  // Unsubscribes the PrefMember from the PrefService. After calling this
-  // function, the PrefMember may not be used any more on the UI thread.
-  // Assuming |MoveToThread| was previously called, |GetValue|, |IsManaged|,
-  // and |IsUserModifiable| can still be called from the other thread but
-  // the results will no longer update from the PrefService.
-  // This method should only be called on the UI thread.
-  void Destroy() {
-    subtle::PrefMemberBase::Destroy();
-  }
-
-  // Moves the PrefMember to another thread, allowing read accesses from there.
-  // Changes from the PrefService will be propagated asynchronously
-  // via PostTask.
-  // This method should only be used from the thread the PrefMember is currently
-  // on, which is the UI thread by default.
-  void MoveToThread(scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
-    subtle::PrefMemberBase::MoveToThread(task_runner);
-  }
-
-  // Check whether the pref is managed, i.e. controlled externally through
-  // enterprise configuration management (e.g. windows group policy). Returns
-  // false for unknown prefs.
-  // This method should only be used from the thread the PrefMember is currently
-  // on, which is the UI thread unless changed by |MoveToThread|.
-  bool IsManaged() const {
-    VerifyPref();
-    return internal_->IsManaged();
-  }
-
-  // Checks whether the pref can be modified by the user. This returns false
-  // when the pref is managed by a policy or an extension, and when a command
-  // line flag overrides the pref.
-  // This method should only be used from the thread the PrefMember is currently
-  // on, which is the UI thread unless changed by |MoveToThread|.
-  bool IsUserModifiable() const {
-    VerifyPref();
-    return internal_->IsUserModifiable();
-  }
-
-  // Retrieve the value of the member variable.
-  // This method should only be used from the thread the PrefMember is currently
-  // on, which is the UI thread unless changed by |MoveToThread|.
-  ValueType GetValue() const {
-    VerifyPref();
-    return internal_->value();
-  }
-
-  // Provided as a convenience.
-  ValueType operator*() const {
-    return GetValue();
-  }
-
-  // Set the value of the member variable.
-  // This method should only be called on the UI thread.
-  void SetValue(const ValueType& value) {
-    VerifyValuePrefName();
-    setting_value_ = true;
-    UpdatePref(value);
-    setting_value_ = false;
-  }
-
-  // Returns the pref name.
-  const std::string& GetPrefName() const {
-    return pref_name();
-  }
-
- private:
-  class Internal : public subtle::PrefMemberBase::Internal {
-   public:
-    Internal() : value_(ValueType()) {}
-
-    ValueType value() {
-      CheckOnCorrectThread();
-      return value_;
-    }
-
-   protected:
-    ~Internal() override {}
-
-    BASE_PREFS_EXPORT bool UpdateValueInternal(
-        const base::Value& value) const override;
-
-    // We cache the value of the pref so we don't have to keep walking the pref
-    // tree.
-    mutable ValueType value_;
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(Internal);
-  };
-
-  Internal* internal() const override { return internal_.get(); }
-  void CreateInternal() const override { internal_ = new Internal(); }
-
-  // This method is used to do the actual sync with pref of the specified type.
-  void BASE_PREFS_EXPORT UpdatePref(const ValueType& value);
-
-  mutable scoped_refptr<Internal> internal_;
-
-  DISALLOW_COPY_AND_ASSIGN(PrefMember);
-};
-
-// Declaration of template specialization need to be repeated here
-// specifically for each specialization (rather than just once above)
-// or at least one of our compilers won't be happy in all cases.
-// Specifically, it was failing on ChromeOS with a complaint about
-// PrefMember<FilePath>::UpdateValueInternal not being defined when
-// built in a chroot with the following parameters:
-//
-// FEATURES="noclean nostrip" USE="-chrome_debug -chrome_remoting
-// -chrome_internal -chrome_pdf component_build"
-// ~/trunk/goma/goma-wrapper cros_chrome_make --board=${BOARD}
-// --install --runhooks
-
-template <>
-BASE_PREFS_EXPORT void PrefMember<bool>::UpdatePref(const bool& value);
-
-template <>
-BASE_PREFS_EXPORT bool PrefMember<bool>::Internal::UpdateValueInternal(
-    const base::Value& value) const;
-
-template <>
-BASE_PREFS_EXPORT void PrefMember<int>::UpdatePref(const int& value);
-
-template <>
-BASE_PREFS_EXPORT bool PrefMember<int>::Internal::UpdateValueInternal(
-    const base::Value& value) const;
-
-template <>
-BASE_PREFS_EXPORT void PrefMember<double>::UpdatePref(const double& value);
-
-template <>
-BASE_PREFS_EXPORT bool PrefMember<double>::Internal::UpdateValueInternal(
-    const base::Value& value) const;
-
-template <>
-BASE_PREFS_EXPORT void PrefMember<std::string>::UpdatePref(
-    const std::string& value);
-
-template <>
-BASE_PREFS_EXPORT bool PrefMember<std::string>::Internal::UpdateValueInternal(
-    const base::Value& value) const;
-
-template <>
-BASE_PREFS_EXPORT void PrefMember<base::FilePath>::UpdatePref(
-    const base::FilePath& value);
-
-template <>
-BASE_PREFS_EXPORT bool
-PrefMember<base::FilePath>::Internal::UpdateValueInternal(
-    const base::Value& value) const;
-
-template <>
-BASE_PREFS_EXPORT void PrefMember<std::vector<std::string> >::UpdatePref(
-    const std::vector<std::string>& value);
-
-template <>
-BASE_PREFS_EXPORT bool
-PrefMember<std::vector<std::string> >::Internal::UpdateValueInternal(
-    const base::Value& value) const;
-
-typedef PrefMember<bool> BooleanPrefMember;
-typedef PrefMember<int> IntegerPrefMember;
-typedef PrefMember<double> DoublePrefMember;
-typedef PrefMember<std::string> StringPrefMember;
-typedef PrefMember<base::FilePath> FilePathPrefMember;
-// This preference member is expensive for large string arrays.
-typedef PrefMember<std::vector<std::string> > StringListPrefMember;
-
-#endif  // BASE_PREFS_PREF_MEMBER_H_
+// TODO(brettw) remove this forwarding header when prefs is completely moved to
+// components.
+#include "components/prefs/pref_member.h"